A class of semiconductor switching elements called power semiconductor devices are used to aid in powering heavy loads, such as large appliances and motors for electric vehicles and hybrids, that require high currents, for instance in the hundreds of amperes. These semiconductor switching elements include devices such as Insulated Gate Bipolar Transistors (IGBTs) and power Metal-Oxide Semiconductor Field Effect Transistors (MOSFETs).
Overloading the semiconductor switching element during operation can be a concern. Particularly, exceeding a voltage rating across the current terminals of the device could permanently damage and/or destroy the device. One conventional technique of controlling the voltage across the current terminals of the semiconductor switching element is to couple a fixed resistance to a control terminal of the device. This fixed resistance can be set to prevent the voltage across the current terminals of the semiconductor switching element from exceeding its voltage rating. However, an undesirable effect is that the fixed resistance also fixes the turn-off speed of the semiconductor switching element, thereby, causing it to operate at lower than optimal turn-off speeds for a good portion of its operating time. The sub-optimal turn-off speeds lead to higher switching losses and a lower system efficiency.
The present disclosure is illustrated by way of example and is not limited by the accompanying figures, in which like reference numbers indicate similar elements. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present disclosure.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Also, the functions included in the flow diagrams do not imply a required order of performing the functionality contained therein.